Thermostatic device



Oct. 13, 1925- 1,557,535

G. H. WHITTINGHAM THERMOSTATIC DEVI GE Filed March 17. 1924 4l l Fig. 1 is a front elevation, partly reuma occas, 1925,.

y1,551,535' ausm' carica.

Yommen n. wm'n'monal, or namnronn, mmv, Assmann 'ro xourron coN- rnonnn conm, or namens, mmm, a coaronanon `or KABY- TmlOSTATIC DEVICE.

MID.

- appumn um umn 17,1924. semi 1ro. 899,955.

To all whom it may concern:

Be it known that I, Gnoaon H. Wm'rrmo- 11AM, a citizen of the United States, residing at Baltimore, in the State of Ma land, have l invented certain new and usefu Improvements in Thermostatic Devices, of which the following is a specification.

This invention relates to a thermally operated device for controlling switches 1n an l electric circuit, although it may be used for a variety of other purposes. The invention comprises a closed metal tube filled with an expansible liquid and having two sections, one corrugated and expansible-by the presll sure of the liquid, and the other relatively7 inexpansible by the liquid pressure. The device is mounted upon a suitable support, with the expansible section below the mexpansible section, and a heating element is $0 arranged adjacent the inexpansible section. With this arrangement, the heat is applied to the liquid through the upper inexpansible section only, and the expanslon of the liquid in this section causes the forcible'e ansion of the lower section which is notxdirectly affected by the heat from the heating element. This'arrangement gives greater precision to the operation of the ex ansble section than if the heat were app ied directly l0 to it. In the preferred arrangement, a heating coil is arranged around the upper section of the tube, and this coil is surrounded by a housing, of heat insulating material. which has openings to permit of the upward Il circulation of air through the housing to carry oif the heat and permit the coil and the tube to coolwhen the current in the coil decreases or is cut off. The heated air thus travels in a direction away from the expansible section of the tube, and this latter section is also preferably shielded from the heating element by a shelf which forms an abutment for said section.

In the accompanying drawing,

1n section, of a unit comprising two thermally operated devices embodying my improvements and arranged to actuate a switch lever which is common to the two devices; Y, l0 Fig. 2 is a side elevation of the same; and,

Fig. 3 is a top plan view of the same. Referring to the drawing, a indicates a aux' ble base upon which is secured a sheet back-piece 1, having attached to lts u per end .a shelf 2 of insulating material w Ich pro]ects forwardly from the base.

vThe metal back-piece has'a forward projecttion 3 at its lower end upon which is pivotally mounted an elbow lever 4.' A spring 5, interposed between the shelf 2 and the shorter arm 4 of the lever. constantly tends to hold the end 4b of the longer arm of the section 9, adapted to be expanded by the ex-` pansive force of the liquid, and a plain section 10, which is inexpansible by the force of the liquid. A shoulder 9a is provided on the tube at the junction of the two sections and this shoulder fits against a shoulder 7, within the bushing 7 The corrugated section of the tube is interposed between said shoulder and the horizontal part 4 of the longer arm of the lever 4. The plain section of the tube extends upwardly above the shelf 2 and is surrounded by a heating coil 11, which is enclosed within a two-part housing 12, which housing is made of insulating material and closely surrounds the tube and holds the coil in a position which is substantially concentric with the axis of the tube. The housing is composed of two similar members 12a, provided with lugs 12b and secured together by screws 13 which passthrough the lugs and into posts 14 which are attached toa block 15, secured to the base a. As shown best in Fig. 3, the ends of the housing are provided with heads 16 which have centraluopenings to receive the tube, and radial slots 17 for permitting the air to flow upwardly through the housing to cool the coil and tube when the current in the coil is reduced or cut oif. As

shown in the drawing, the ends of each coil are connected to suitable binding posts 18 which may be connected to the current source. It is to be noted that with the ar rangement described, the expansion section of each tube is below the heatin element and also shielded from it by the s elf, and

vlever against a contact member 6 on the forconnected in different legs tube is forcibly expanded by that the heat is a plied directly only to the upEr inexpansib 'e ofthe tube.

operation, the 'quid in the upmnpart of the tube becomes heated ,by heat the surrounding coil and as the liquid expands with heat, the corruga the liquid and p the switch arm or ever 4 to o position against the tension of the, s ring 5. B adjusting the sleeve or socket u ward y or downwardly, the tube will be a lowed to expand to a greater or less extent before causing the actuation of the switch. When the current in the heating coil falls or is cut oil' the upper part of the tube and the liquid therein wiii w01 and the msible portion of the tube will then contract and rm'it the switch to close. In order that e device may work properly, the heat should be prevented from accumulating in the housing surrounding the tube, and for thispurpcsetheo 'gs17 are i'ovided in the heads of the ousing so that t e excess heat will be carried o by the 'iiward ow of air through the housing. is upward ilow also carries the heat in the direction away from the expansible `section of the tube, which is desirable, since it is the purpose to have this section oerate by the expansible force of the liqui rather than by theheating of the section, or of the liquid therein. Y

It will be understood from the arrangement shown in the drawing that the switch lever will be operated by the expansion of either of the tubes. Thus, if the coils be of a multi-phase motor circuit, an excessive current flowing in either leg will cause the action of the switch. This is one purpose of the invention. It will be obvious that the invention -may be appliedto various uses.

What I claim is: 1. The combination with suitable supporting means, of a thermostatic device mounted tudinally b a relative]y ted section 9 of the h thereon and comprising' a closed tube filled with an expansib e liquid, said tube having ted section s prequre of liquid and inexpansible usper section, `a eating co surrounding sai upper section, an d ashield of insulating material between said coil and the lower section. 2. lThe combination with suitable supportmg means, of a thermostatic device mountedthereonandcom aclosedtube filled with an expansible quid, said tube h avin a .lower corrugated section sible ongitudinally the pressure og the liquid and a relativ y inexpansible upper section, and a heating coil surrounding said upper section. p 3. The combination with suitable supporting means, of a thermostatic device mounted thereon and com r' a closed tube filled with an expansib e liquid, said tube having a lower corrugated section expansible longitudinally by the pressure of the liquid and a relativell inexpaiisible u r section, a heating co' .surrounding sai upier section, and a housing surrounding sai coil, said housing having openings to rmit the upward circulation of air the rough. 4. The combination with suitable supportmg means, of a thermostatic device mounted thereon and compri a closed tube containing an expansible liquid, said tube having a lo wer co ted section expansible longitudinally by the pressure of the liquid and a relatively inexpansible u per section, a heat' coil surrounding sai upper section an a housing surrounding said coil and adapted to hold the same in concentric position with respect to the axis of the tube, said housing having openings to permit circulation of air therethro h.

In testimony whereof lIghereunto atlix my signature.

GEORGE H. WHITTINGI-IAM.

a lower co 'ble longi- 

